To measure any temporal changes in the relative avidity of the antibody populations to herpesvirus membrane antigens and correlate these findings with ADCC and disease patterns in both lymphomatous owl monkeys and in humans with NPC. To fractionate serial serum samples from lymphomatous owl monkeys and patients with NPC into their separate immunoglobulin classes (IgG, IgM, IgA) and determine their specific binding to herpesvirus MA and the function of each class in vivo and in vitro in mediating or blocking ADCC reactions. To investigate the possibility of immune complexes appearing during malignant progression in owl monkeys and their role in influencing in vivo and in vitro ADCC reactions. To correlate the qualitative factors determined in this study with existing pathological finding and antibody titers to ascertain the function of humoral antibody in the control of herpesvirus-mediated malignancies.